The present invention may relate to a combined-drive bicycle, more particularly, to a combined-drive bicycle which can increase a driving speed and the beneficial effects of exercise and simultaneously to give fun to a rider.
Generally, a bicycle is a vehicle with two wheels which a person rides by sitting on it and pushing two pedals with his or her feet and which he or she steers by turning a bar connected to the front wheel with the hands.
In an aspect of the user's exercise, the beneficial effects of leg exercise are great and the beneficial effects of arm exercise are little. Also, the driving speed is limited.
In the meanwhile, to overcome such a disadvantage, there have been efforts at improvement of the structure of the bicycle to enable the rider to use his or her arms and legs multiply in riding the bicycle.
However, even an improved bicycle might have a disadvantage such as a complex structure, inconvenience of different speeds generated in front and rear wheels, or unnatural driving of his or her arms.
Moreover, the arms and the pedals rotated by the legs are moving in communication with each other. Because of that, a pedal shaft of the handle might be rotated disadvantageously even when the pedals are driven by the legs.
Also, when the rider rotates a handle to drive the bicycle using the strength of his or her arms, a steering shaft of the front wheel might fail to be steered because of the influence of the handle rotation.
As a result, there have been increasing demands for development of a bicycle that can be manufactured by transforming a conventional bicycle easily, that can be driven only by the strength of the rider's arms or legs or only by the strength of both of the rider's arms and legs, that enables the rider's arms and legs to move naturally in a biomechanical aspect, with increasing the driving speed as well as the exercise effects and with giving fun to the rider simultaneously.
Furthermore, there have been increasing demands for a power transmission structure that can prevent a steering shaft from being affected by the rotation of the handle performed to drive a bicycle using the strength of the rider's arms.